The field of art to which this invention relates is instruments for cardiac surgery, in particular, cardiac stabilizer devices and methods of using such stabilizers in cardiac surgical procedures.
Open chest cardiac surgical procedures have become common in the treatment of heart disease. These procedures include, for example, coronary artery bypass graft surgery, heart valve replacement, anastomosis procedures, aneurysm repairs, etc. Many of these procedures can now be performed as closed chest procedures using endoscopic surgical instruments and minimally invasive techniques, and additional procedures are continually being adapted as minimally invasive procedures.
Of particular interest are coronary artery bypass graft (CABG) procedures, since these are the most commonly performed cardiac surgical procedures. In conventional CABG procedures, a section of saphenous vein is typically harvested from the patient""s leg. As an alternative to using a section of vein, a section of the radial artery may be harvested and used. The harvested section of blood vessel is then used to bypass blockages or lesions in various coronary arteries by performing anastomosis procedures to connect the aorta to the distal or downstream sides of the blocked vessels, thereby re-establishing oxygenated blood flow to the areas of the heart muscle which had been deprived because of the blockages. Another procedure that is commonly use in CABG procedures is the harvesting of an internal mammary artery (IMA) as a source of oxygenated blood for a bypass graft procedure. The harvested end of the IMA is attached via an anastomosis to a section of cardiac artery distal to the lesion or blockage site.
CABG procedures have conventionally been performed by stopping the patient""s heart and utilizing a cardiopulmonary bypass procedure, wherein blood is shunted from the peripheral vascular system around the heart and the lungs to an external pump and blood oxygenator, and then back to the peripheral vascular system. It is known that there are many disadvantages and side effects associated with cardiopulmonary bypass, although the potential life-saving benefits of the procedure outweigh the risks for most patients. It is believed that the severity of the side effects tends to increase with the duration of the procedure.
Accordingly, cardiac surgical procedures that utilized cardiopulmonary bypass have been designed to be as time efficient as possible.
In order to attempt to improve surgical outcomes of CABG procedures, there has been a recent trend toward beating heart surgery. A major advantage of beating heart surgery is that it eliminates the need for cardiopulmonary bypass. However, beating heart surgery offers challenges to the surgeon in completing the CABG procedure. In particular, in order to perform an anastomosis, delicate vessel attachment procedures must be performed while the heart is moving as it beats. It can be appreciated by those skilled in the art that the surface of a beating heart is in a constant state of motion with relatively large cyclic movements or displacements. Therefore, in order to conduct a beating heart cardiac operation, it is necessary to stabilize at least a portion of the beating heart in the area of the vessel anastomoses.
Cardiac stabilizers have been developed and are known in the art to provide effective heart stabilization during a CABG procedure in both beating heart and stopped heart procedures. The stabilizers typically have an elongated tube or shaft with a pair of feet, or an arcuate member, mounted transversely to the distal end of the shaft. The feet are typically articulable with respect to the shaft in order to adjust to the contoured surfaces of the heart. In order to provide for improved cardiac stabilization, it is known to add vacuum ports to the feet, which are connected to a vacuum source in the tube. It is believed that the vacuum causes the surface of cardiac tissue adjacent to a vacuum port to be engaged by that port, thereby assisting in the stabilization of the beating heart. Another type of cardiac stabilizer is disclosed in U.S. Pat. No. 5,865,730, which is incorporated by reference. This stabilizer uses downward force to stabilize the heart while having a vacuum source connected to the tube to assist in stabilizing the heart, as well as providing a pathway to remove fluids and loose tissue in the vicinity of the anastomosis sites.
Although utilizing vacuum with a mechanical stabilizer has been shown to be advantageous, there may be side effects associated with the use of vacuum. For example, if the vacuum source is too intense or applied for an extended period of time, myocardial hematomas may be formed in the myocardial tissue in and about the vacuum port areas. The formation of myocardial hematomas is undesirable because they may be associated with myocardial cell damage and healing by fibrosis, resulting in reduced contractility at the site of application, and other known complications.
Accordingly, there is a need in this art for improved heart stabilizers that utilize vacuum to stabilize a heart and which minimize or eliminate the incidence of side effects such as the development of hematomas on the heart and damage to the subjacent myocardium during a stabilization procedure.
It is an object of the present invention to provide a cardiac stabilizer device that when used with a vacuum decreases the incidence of hematomas on and beneath the surface of the heart.
It is yet another object of the present invention to provide a method of stabilizing a heart with a cardiac stabilizer using a multiplexed vacuum source connected to the stabilizer.
Accordingly, a cardiac stabilizer device is disclosed. The cardiac stabilizer device has an elongated member having a proximal end and a distal end. At least one foot member is mounted to the distal end of the elongated member. The foot member has at least two tissue engagement vacuum port openings. At least two pressure tubes are mounted to the elongated member, the pressure tubes each have a proximal end, a distal and an inner lumen. Each vacuum port opening is in fluid communication with the lumen of one of pressure tubes so that the vacuum or pressure level in each port opening is individually controlled.
Another aspect of the present invention is a cardiac vacuum stabilizer having an articulable elongated member consisting of interlocking components or segments that are operable with each other. The articulable elongated member has a proximal end and a distal end. At least one foot member is mounted to the distal end of the elongated member. The foot member has at least two tissue engagement vacuum port openings. At least two pressure tubes are mounted to the elongated member, the pressure tubes each have a proximal end, a distal end, and an inner lumen. Each vacuum port opening is in fluid communication with the lumen of one of pressure tubes so that the vacuum or pressure level in each port opening is individually controlled. The elongated member may be locked into a fixed position by tensioning a flexible member associated with the elongated member.
Still yet another aspect of the present invention is a cardiac vacuum stabilizer. The cardiac stabilizer device has an elongated member having a proximal end and a distal end formed from at least two pressure tubes. At least one foot member is mounted to the distal end of the elongated member. The foot member has at least two tissue engagement vacuum port openings. The pressure tubes each have a proximal end, a distal end, and an inner lumen. Each vacuum port opening is in fluid communication with the lumen of one of pressure tubes so that the vacuum or pressure level in each port opening is individually controlled.
Yet another aspect of the present invention is the combination of the previously described cardiac stabilizers and a multiplexing vacuum source. The vacuum source cyclically varies or multiplexes the vacuum to each individual vacuum port from a high level effective for tissue engagement to a lower level effective to allow blood perfusion in the engaged cardiac tissue.
An additional aspect of the present invention is a method of stabilizing a beating heart during cardiac surgery. The method consists of initially providing a cardiac stabilizer device. The cardiac stabilizer device has an elongated member having a proximal end and a distal end. At least one foot member is mounted to the distal end of the elongated member. The foot member has at least two tissue engagement vacuum port openings. At least two pressure tubes are mounted to the elongated member. The pressure tubes each have a proximal end, a distal end, and an inner lumen. Each vacuum port opening of the foot member is in fluid communication with the lumen of one of the pressure tubes. The top of each pressure tube is connected to a source of vacuum. The foot member is rested upon the surface of a heart and engages and stabilizes the heart in the vicinity of the foot member. The vacuum in each tube is individually controlled so that cardiac tissue is engaged by each tissue engagement vacuum port and the pressure level varies cyclically in each vacuum port between a first negative pressure and a second higher pressure.
These and other aspects and advantages of the present invention will become more apparent from the accompanying drawings and following description.